[Federal Register Volume 76, Number 30 (Monday, February 14, 2011)]
[Proposed Rules]
[Pages 8316-8319]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-3215]
[[Page 8316]]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM442 Special Conditions No. 25-11-02-SC]
Special Conditions: Gulfstream Model GVI Airplane; Interaction of
Systems and Structures
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Notice of proposed special conditions.
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SUMMARY: This action proposes special conditions for the Gulfstream GVI
airplane. This airplane will have novel or unusual design features when
compared to the state of technology envisioned in the airworthiness
standards for transport category airplanes. These design features
include systems that affect the structural capability of the airplane.
The applicable airworthiness regulations do not contain adequate or
appropriate safety standards for these design features. The proposed
special conditions contain the additional safety standards that the
Administrator considers necessary to establish a level of safety
equivalent to that established by the existing airworthiness standards.
DATES: We must receive your comments by March 31, 2011.
ADDRESSES: You must mail two copies of your comments to: Federal
Aviation Administration, Transport Airplane Directorate, Attn: Rules
Docket (ANM-113), Docket No. NM442, 1601 Lind Avenue, SW., Renton,
Washington 98057-3356. You may deliver two copies to the Transport
Airplane Directorate at the above address. You must mark your comments:
Docket No. NM442. You can inspect comments in the Rules Docket
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: Carl Niedermeyer, FAA, Airframe/Cabin
Safety Branch, ANM-115, Transport Standards Staff, Transport Airplane
Directorate, Aircraft Certification Service, 1601 Lind Avenue, SW.,
Renton, Washington 98057-3356; telephone (425) 227-2279; facsimile
(425) 227-1320.
SUPPLEMENTARY INFORMATION:
Comments Invited
We invite interested people to take part in this rulemaking by
sending written comments, data, or views. The most helpful comments
reference a specific portion of the special conditions, explain the
reason for any recommended change, and include supporting data. We ask
that you send us two copies of written comments.
We will file in the docket all comments we receive, as well as a
report summarizing each substantive public contact with FAA personnel
concerning these special conditions. You can inspect the docket before
and after the comment closing date. If you wish to review the docket in
person, go to the address in the ADDRESSES section of this preamble
between 7:30 a.m. and 4 p.m., Monday through Friday, except Federal
holidays.
We will consider all comments we receive on or before the closing
date for comments. We will consider comments filed late if it is
possible to do so without incurring expense or delay. We may change
these special conditions based on the comments we receive.
If you want us to acknowledge receipt of your comments on this
proposal, include with your comments a self-addressed, stamped postcard
on which you have written the docket number. We will stamp the date on
the postcard and mail it back to you.
Background
On March 29, 2005, Gulfstream Aerospace Corporation (hereafter
referred to as ``Gulfstream'') applied for an FAA type certificate for
its new Gulfstream Model GVI passenger airplane. Gulfstream later
applied for, and was granted, an extension of time for the type
certificate, which changed the effective application date to September
28, 2006. The Gulfstream Model GVI airplane will be an all-new, two-
engine jet transport airplane with an executive cabin interior. The
maximum takeoff weight will be 99,600 pounds, with a maximum passenger
count of 19 passengers.
Type Certification Basis
Under provisions of Title 14, Code of Federal Regulations (14 CFR)
21.17, Gulfstream must show that the Gulfstream Model GVI airplane
(hereafter referred to as ``the GVI'') meets the applicable provisions
of 14 CFR part 25, as amended by Amendments 25-1 through 25-119, 25-
122, and 25-124. If the Administrator finds that the applicable
airworthiness regulations (i.e., 14 CFR part 25) do not contain
adequate or appropriate safety standards for the GVI because of a novel
or unusual design feature, special conditions are prescribed under the
provisions of Sec. 21.16.
In addition to complying with the applicable airworthiness
regulations and special conditions, the GVI must comply with the fuel
vent and exhaust emission requirements of 14 CFR part 34 and the noise
certification requirements of 14 CFR part 36. The FAA must also issue a
finding of regulatory adequacy pursuant to section 611 of Public Law
92-574, the ``Noise Control Act of 1972.''
The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec. 11.38, and they become part of the type
certification basis under Sec. 21.17(a)(2).
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same novel or
unusual design features, the special conditions would also apply to the
other model under provisions of Sec. 21.101.
Novel or Unusual Design Features
The Model GVI airplane will incorporate novel or unusual design
features. These features are systems that may affect the airplane's
structural performance, either directly or as a result of failure or
malfunction. That is, the airplane's systems affect how it responds in
maneuver and gust conditions, and thereby affect its structural
capability. These systems may also affect the aeroelastic stability of
the airplane. These systems include the GVI's flight control systems,
autopilots, stability augmentation systems, load alleviation systems,
and fuel management systems. Such systems represent a novel and unusual
feature when compared to the technology envisioned in the current
airworthiness standards.
Discussion of Proposed Special Conditions
Special conditions are needed to require consideration of the
effects of systems on the structural capability and aeroelastic
stability of the airplane, both in the normal and in the failed state,
because these effects are not covered by current regulations.
These proposed special conditions are identical or nearly identical
to those previously required for type certification of other transport
airplane models. These proposed special conditions were derived
initially from standardized requirements developed by the Aviation
Rulemaking Advisory Committee (ARAC), comprised of representatives of
the FAA, Europe's Joint Aviation Authorities (now replaced by the
European Aviation Safety Agency), and industry.
[[Page 8317]]
These proposed special conditions require that the airplane meets
the structural requirements of subparts C and D of 14 CFR part 25 when
the airplane systems are fully operative. These proposed special
conditions also require that the airplane meet these requirements
considering failure conditions. In some cases, reduced margins are
allowed for failure conditions based on system reliability.
These special conditions establish a level of safety that neither
raises nor lowers the standard set forth in the applicable regulations.
In these proposed special conditions and in the current standards
and regulations, the term ``any'' is used. Use of this term has
traditionally been understood to require all items covered by the term
are addressed, rather than addressing only a portion of the items. The
use of the term ``any'' in these proposed special conditions continues
this traditional understanding.
Applicability
As discussed above, these proposed special conditions are
applicable to the GVI. Should Gulfstream apply at a later date for a
change to the type certificate to include another model incorporating
the same novel or unusual design features, these proposed special
conditions would apply to that model as well.
Conclusion
This action affects only certain novel or unusual design features
of the GVI. It is not a rule of general applicability.
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
The authority citation for this special condition is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Proposed Special Conditions
Accordingly, the Federal Aviation Administration (FAA) proposes the
following special conditions as part of the type certification basis
for the GVI airplanes.
A. General
The GVI is equipped with systems that affect structural
performance, either directly or as a result of a failure or
malfunction. The influence of these systems and their failure
conditions on structural performance must be taken into account when
showing compliance with the requirements of Subparts C and D of part 25
of Title 14, Code of Federal Regulations.
1. The following criteria must be used for showing compliance with
this proposed special condition for airplanes equipped with flight
control systems, autopilots, stability augmentation systems, load
alleviation systems, fuel management systems, and other systems that
either directly or as a result of failure or malfunction affect
structural performance.
2. The criteria defined herein only address the direct structural
consequences of the system responses and performance. They cannot be
considered in isolation but should be included in the overall safety
evaluation of the airplane. These criteria may in some instances
duplicate standards already established for this evaluation. These
criteria are only applicable to structure whose failure could prevent
continued safe flight and landing. Specific criteria that define
acceptable limits on handling characteristics or stability requirements
when operating in the system degraded or inoperative mode are not
provided in this proposed special condition.
3. Depending upon the specific characteristics of the airplane,
additional studies may be required that go beyond the criteria provided
in this proposed special condition in order to demonstrate the
capability of the airplane to meet other realistic conditions such as
alternative gust or maneuver descriptions for an airplane equipped with
a load alleviation system.
4. The following definitions are applicable to this proposed
special condition.
(a) Structural performance: Capability of the airplane to meet the
structural requirements of 14 CFR part 25.
(b) Flight limitations: Limitations that can be applied to the
airplane flight conditions following an in-flight occurrence and that
are included in the flight manual (e.g., speed limitations, avoidance
of severe weather conditions, etc.).
(c) Operational limitations: Limitations, including flight
limitations, that can be applied to the airplane operating conditions
before dispatch (e.g., fuel, payload and master minimum equipment list
limitations).
(d) Probabilistic terms: The probabilistic terms (probable,
improbable, extremely improbable) used in this proposed special
condition are the same as those used in Sec. 25.1309.
(e) Failure condition: The term failure condition is the same as
that used in Sec. 25.1309; however, this proposed special condition
applies only to system failure conditions that affect the structural
performance of the airplane (e.g., system failure conditions that
induce loads, change the response of the airplane to inputs such as
gusts or pilot actions, or lower flutter margins).
B. Effects of Systems on Structures
1. General. The following criteria will be used in determining the
influence of a system and its failure conditions on the airplane
structure.
2. System fully operative. With the system fully operative, the
following apply:
(a) Limit loads must be derived in all normal operating
configurations of the system from all the limit conditions specified in
Subpart C (or used in lieu of those specified in Subpart C), taking
into account any special behavior of such a system or associated
functions or any effect on the structural performance of the airplane
that may occur up to the limit loads. In particular, any significant
nonlinearity (rate of displacement of control surface, thresholds or
any other system nonlinearities) must be accounted for in a realistic
or conservative way when deriving limit loads from limit conditions.
(b) The airplane must meet the strength requirements of part 25
(static strength, residual strength), using the specified factors to
derive ultimate loads from the limit loads defined above. The effect of
nonlinearities must be investigated beyond limit conditions to ensure
the behavior of the system presents no anomaly compared to the behavior
below limit conditions. However, conditions beyond limit conditions
need not be considered when it can be shown that the airplane has
design features that will not allow it to exceed those limit
conditions.
(c) The airplane must meet the aeroelastic stability requirements
of Sec. 25.629.
3. System in the failure condition. For any system failure
condition not shown to be extremely improbable, the following apply:
(a) At the time of occurrence. Starting from 1-g level flight
conditions, a realistic scenario, including pilot corrective actions,
must be established to determine the loads occurring at the time of
failure and immediately after the failure.
(1) For static strength substantiation, these loads multiplied by
an appropriate factor of safety that is related to the probability of
occurrence of the failure are ultimate loads to be considered for
design. The factor of safety (FS) is defined in Figure 1.
[[Page 8318]]
[GRAPHIC] [TIFF OMITTED] TP14FE11.012
(2) For residual strength substantiation, the airplane must be able
to withstand two thirds of the ultimate loads defined in subparagraph
B.3(a)(1). For pressurized cabins, these loads must be combined with
the normal operating differential pressure.
(3) Freedom from aeroelastic instability must be shown up to the
speeds defined in Sec. 25.629(b)(2). For failure conditions that
result in speeds beyond VC/MC, freedom from
aeroelastic instability must be shown to increased speeds, so that the
margins intended by Sec. 25.629(b)(2) are maintained.
(4) Failures of the system that result in forced structural
vibrations (oscillatory failures) must not produce loads that could
result in detrimental deformation of primary structure.
(b) For the continuation of the flight. For the airplane in the
system failed state, and considering any appropriate reconfiguration
and flight limitations, the following apply:
(1) The loads derived from the following conditions (or used in
lieu of the following conditions) at speeds up to VC/
MC (or the speed limitation prescribed for the remainder of
the flight) must be determined:
(i) The limit symmetrical maneuvering conditions specified in Sec.
25.331 and in Sec. 25.345.
(ii) The limit gust and turbulence conditions specified in Sec.
25.341 and in Sec. 25.345.
(iii) The limit rolling conditions specified in Sec. 25.349 and
the limit unsymmetrical conditions specified in Sec. 25.367 and Sec.
25.427(b) and (c).
(iv) The limit yaw maneuvering conditions specified in Sec.
25.351.
(v) The limit ground loading conditions specified in Sec. 25.473
and Sec. 25.491.
(2) For static strength substantiation, each part of the structure
must be able to withstand the loads in paragraph B.3(b)(1) of this
proposed special condition multiplied by a factor of safety depending
on the probability of being in this failure state. The factor of safety
is defined in Figure 2.
[GRAPHIC] [TIFF OMITTED] TP14FE11.013
Qj = (Tj)(Pj)
Where:
Qj = Probability of being in failure condition j
Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per hour)
Note: If Pj is greater than 10-3 per flight hour
then a 1.5 factor of safety must be applied to all limit load
conditions specified in Subpart C.
(3) For residual strength substantiation, the airplane must be able
to withstand two thirds of the ultimate loads defined in paragraph
B.3(b)(2) of this proposed special condition. For pressurized cabins,
these loads must be combined with the normal operating differential
pressure.
(4) If the loads induced by the failure condition have a
significant effect on fatigue or damage tolerance then their effects
must be taken into account.
(5) Freedom from aeroelastic instability must be shown up to a
speed determined from Figure 3. Flutter clearance speeds V' and V'' may
be
[[Page 8319]]
based on the speed limitation specified for the remainder of the flight
using the margins defined by Sec. 25.629(b).
[GRAPHIC] [TIFF OMITTED] TP14FE11.014
V' = Clearance speed as defined by Sec. 25.629(b)(2).
V'' = Clearance speed as defined by Sec. 25.629(b)(1).
Qj = (Tj)(Pj) where:
Qj = Probability of being in failure condition j
Tj = Average time spent in failure condition j (in hours)
Pj = Probability of occurrence of failure mode j (per hour)
Note: If Pj is greater than 10-3 per flight hour,
then the flutter clearance speed must not be less than V''.
(6) Freedom from aeroelastic instability must also be shown up to
V' in Figure 3 above, for any probable system failure condition
combined with any damage required or selected for investigation by
Sec. 25.571(b).
(c) Consideration of certain failure conditions may be required by
other sections of 14 CFR part 25 regardless of calculated system
reliability. Where analysis shows the probability of these failure
conditions to be less than 10-9, criteria other than those
specified in this paragraph may be used for structural substantiation
to show continued safe flight and landing.
4. Failure indications. For system failure detection and
indication, the following apply:
(a) The system must be checked for failure conditions, not
extremely improbable, that degrade the structural capability below the
level required by part 25 or significantly reduce the reliability of
the remaining system. As far as reasonably practicable, the flight crew
must be made aware of these failures before flight. Certain elements of
the control system, such as mechanical and hydraulic components, may
use special periodic inspections, and electronic components may use
daily checks, in lieu of detection and indication systems to achieve
the objective of this requirement. These certification maintenance
requirements must be limited to components that are not readily
detectable by normal detection and indication systems, and where
service history shows that inspections will provide an adequate level
of safety.
(b) The existence of any failure condition, not extremely
improbable, during flight that could significantly affect the
structural capability of the airplane and for which the associated
reduction in airworthiness can be minimized by suitable flight
limitations, must be signaled to the flight crew. For example, failure
conditions that result in a factor of safety between the airplane
strength and the loads of Subpart C below 1.25, or flutter margins
below V'', must be signaled to the crew during flight.
5. Dispatch with known failure conditions. If the airplane is to be
dispatched in a known system failure condition that affects structural
performance, or that affects the reliability of the remaining system to
maintain structural performance, then the provisions of this proposed
special condition must be met, including the provisions of paragraph
B.2 for the dispatched condition and paragraph B.3 for subsequent
failures. Expected operational limitations may be taken into account in
establishing Pj as the probability of failure occurrence for
determining the safety margin in Figure 1. Flight limitations and
expected operational limitations may be taken into account in
establishing Qj as the combined probability of being in the dispatched
failure condition and the subsequent failure condition for the safety
margins in Figures 2 and 3. These limitations must be such that the
probability of being in this combined failure state and then
subsequently encountering limit load conditions is extremely
improbable. No reduction in these safety margins is allowed if the
subsequent system failure rate is greater than 1E-3 per hour.
Issued in Renton, Washington, on February 3, 2011.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2011-3215 Filed 2-11-11; 8:45 am]
BILLING CODE 4910-13-P